The Depressed Foal

"We all know this little guy--he's the one who will stand under the mare getting milk dumped on his face without nursing, sleep too much, just look 'off,' and often be in the hospital," said Robert Franklin, DVM, Diplomate ACVIM, of Goulburn Valley Equine Hospital in Victoria, Australia, during the Western Veterinary Conference held February 15-19 in Las Vegas, Nev.

"Start with his history--was he delivered normally? Dystocia? C-section?" he said. "Was there a failure of passive transfer? What about his herdmates--do any of them have rotavirus, strangles, Clostridia, R. equi, or anything else? Look for infectious and/or endemic problems. Has there been previous disease on the farm? Was the mare vaccinated against it? What about the mare's udder--does she have mastitis or an underdeveloped udder? Is she letting the foal suckle? Is he getting enough food?"

Getting More Information

Once you have the foal's background, it's time for a physical examination. Franklin described starting with the basic evaluations--temperature, pulse, respiration, mucous membranes, and sclera (the white part of the eye, which can be yellowed with neonatal isoerythrolysis, also called jaundice). He also recommended checking for any jugular vein problems due to catheter use in previously hospitalized foals, and palpating the entire foal from nose to tail on both sides. With this evaluation, he said a practitioner can find swellings and sensitivities that might not be visible on a cursory visual examination.

The next step is to gather more information, he said, recommending the following evaluations for the depressed foal:

Complete blood count (CBC) and fibrinogen (which indicates inflammation). The CBC gives the practitioner an idea of what's going on with the foal's immune response to infection.

Ultrasound for respiratory problems (see article #5090 for more information).

Radiographs of the chest to check for pneumonia.

Culture of diarrhea, if any is present, to identify Salmonella in the feces and test for rotavirus antigen and Clostridial species toxins.

Culture of blood samples to look for bacteremia (bacteria in the blood).

Common Problems
The most common reasons a foal might become depressed, Franklin said, include infection, poor nutrition, acidosis (unusually acidic blood from diarrhea), lameness (multiple lamenesses can often depress a foal, while just one usually doesn't cause depression), respiratory difficulty, and hypothermia (low body temperature).

Rule of 20
Franklin also presented a comprehensive list of what the foal needs to be healthy, termed the Rule of 20. "If you were to keep the rule of 20 on each of your patients' charts, then you know you've covered absolutely everything," he said. Not everything on the list will apply to each case--for example, the ones dealing with wound care won't apply to uninjured foals--but he said it's a great way to organize your thoughts on what might be wrong with the foal and to prevent complications.

Drug doses and metabolism. "For example, tetracycline (often given to help relax contracted tendons) can lead to renal (kidney) failure. Check creatinine and electrolytes in these foals to identify and head off problems--renal failure isn't always a permanent issue."

Oncotic pull, which keeps fluid from leaking out of the blood vessels; poor oncotic pull can result from hypoproteinemia (low blood protein) and/or diarrhea. Primary treatment for poor oncotic pull (as measured by low protein on blood tests or the presence of subcutaneous edema, or fluid swelling under the skin) is albumin, a type of protein found in plasma, or hetastarch (a plasma substitute).

Albumin (a protein manufactured within the liver that is mostly responsible for water balance within the blood system) is found in commercial equine plasma, which contains other essential proteins such as IgG (an immunoglobulin, or immune system protein).

Glucose (should be 80-160 mg/dL). "The handheld units that diabetic people use are invaluable," Franklin said. "If you have to run glucose into the foal, give it as a drip--don't just run a bag in quickly and be done. You could make him hyperglycemic (high blood sugar) and precipitate a hypoglycemic (low blood sugar) crash. Also, when you take him off the drip, try to add milk by stomach tube so he doesn't crash then."

Mentation (thought processes and attitude/behavior), which can vary from comatose to hyperexcitability and seizure activity.

Renal function. "Sodium imbalances can really cause problems," Franklin noted. "And potassium can stop the heart if it is too high in a foal under anesthesia."

Immune status and antibiotics.

Gastrointestinal motility. "The intestines might be hyperactive in diarrhea cases, or they may be hypomotile (under-active) with botulism leading to impaction,ï¿½ he explained. "Also think about gastroduodenal ulcers, which might obstruct the outflow from the stomach and lead to painful reflux esophagitis (inflammation of the esophagus from acidic stomach contents refluxing back up into the esophagus) seen in teeth-grinding foals."